ninjamouse

Good Day All- a newbie here checked egr-cleaned replaced cooling sensor, fan & ecu-beside of it back of intake drove light came back on i am losing my MIND trfying to figure this out anybody chime in w/suggestions if not some C4 will help... thanks

scope103

It will be easier to figure out what you have done if you throw in a few periods and commas.

Code 71 is to detect a failure of the EGR by measuring the temperature of the exhaust->intake duct. (Too cold means no exhaust getting through.) First, I would put my hand on the duct after you've been driving a bit; I'm told it should be "warm, not hot." If it's cold, the problem is in the EGR circuit. If warm, the problem is in the EGR Gas Temp Sensor.

ninjamouse

tubing to EGR seems warm, how to check temp sensor that is in side of EGR valve ?? Thanks for al your help

n2o302

I got the same code too, I pulled the egr tube out of the intake cleaned, made sure there was no blockage on the vacuum hose come from the tbody to that charcoal filter thing cleaned that from there i pulled the egr off and cleaned that to double checked to make sure that the diaphragm moves up and down freely blew some air thru those holes to check for blockage. After that I put it back together and pulled the efi fuse for 10mins plugged it back together and so far no check engine light. (knocking on wood)

Co_94_PU

iTrader: (-1)

With an ohm meter.
http://personal.utulsa.edu/~nathan-b...43egrgaste.pdf

PS Thanks guys you inspired me to work on mine some more. Bimetal valve works, EGR valve warm, EGR tube to intake cold *bingo* I'll pull that off and hammer the gunk out

Co_94_PU

iTrader: (-1)

No need to wonder, perform the diagnostics driving pattern from the manual page Eg1-120
http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf

scope103

It may take a little more than that. By pulling the EGR tube you can only get so far. During my head gasket replacement, I decided there was a "lot" of gunk inside the plenum (upper intake manifold), and cleaned the whole thing. As a result, my idle-ups (A/C and PS) started working!

It's difficult to get inside the plenum (I used a bottle brush and dishwasher liquid). If I did it again, I'd either have a shop hot-tank it (using aluminum-safe chemistry), or at least knock out the "freeze plugs" in the ends so that I could reach inside.

If your EGR tube slides out and there is a little bit of dirt on it, you're probably okay with a thorough cleaning of the tube. But if you have to actually pull on the tube to get it out, think about the rest of the plenum.

Co_94_PU

iTrader: (-1)

was all excited to get this done last night. But it was bugging me all day long since "I Know that tube is clear because it bogs when I apply vacuum directly to the EGR"

So I'm back to square one, almost. The EGR valve and tubes seem clear, maybe slightly pluged but not completely,the Bimetal valve is operating at some temp(didn't pull it to check but in the ball park I'm sure), The lines are all there and solid.

My only options left are the modulator, throttle body ports, the temp sensor really is bad (even if it seems to check out ok for "room temp"). The only other thing I could think would be an issue is a discrepency between the Bi-metal Vac switch and Ect sensor temps. Both of which I probably should have pulled and cleaned when I had the coolant drained the other day.

I didn't locate an electric vac switch in the loop, but that doesn't completly rule out there should be one(It got a bit chilly out and I came in). I'll need to double check the emissions sticker still.

I'll have a poke around and look for the EGR port details on the plenum, just for my edification on it's layout

ninjamouse

Ya I flushed all lines out with Carb cleaner changed out a few vac lines that looked questionable... reconnected started her up light out, but came back on-DRAG- Back to square one will check temp sensor on EGR tomorrow- is the egr mod filter inside, suppose to get wet, removed cap & inside filter was soaking wet a few days ago has not happened again...Any other suggestions would be great!

Co_94_PU

iTrader: (-1)

It will soak up some astmospheric moisture since it's exposed but generally no it should not be wet.

If you do the test pattern you'll know if it is fixed. It's really simple takes about 15minutes including the initial warm up.

Also to be clear. You need to check for heat in the tube from the egr valve, the tube between the head to the egr valve will heat up due to the flow to the modulator. And it should actually be hot not warm, no less or not much less than the water temp really since it uses the head water jacket to cool it off.

From what scope said about it being difficult to clean I'm assuming there is some sort of convoluted routing and not just a straight hole into the plenum. I can't find a clear picture from the rear end either. I thought it was just a straight thru hole, but if it has odd twists turns or restrictions it could be blocked here in which case every thing else could be working but there won't be flow from the valve to the plenum so the sensor and tube won't heat up.

Someone have a 22re upper intake handy they wouldn't mind getting pictures of, please?

Cyberhorn The Dragon

CO asked for a couple pictures to help out as ive got my engine out an rebuilding (i havent read your thread so forgive me for reposting anything)

the EGR passage into the upper plenum is straight in stuck a screwdriver in just to show this


the EGR pipes of course are convoluted but likely place for a clog is the back of the head in the EGR bypass i had the issue on my 79 20R (its here on the left of the picture about center is where the EGR bolts to the head)

ninjamouse

Thanks this is a 3.0, I pulled tube that went thru intake it was black caked on gunk - cleaned & reinstalled. Light still on. The tube going to EGR valve is not HOT I can hold it with finger no problem.. I have blown out every port I can see in T-body & hose with carb cleaner... light still on..

Co_94_PU

iTrader: (-1)

You've reset the computer by removing the EFI fuse for a minute to clear the code from memory?

When you manually apply vacuum to the EGR valve with the engine running does it bog down and try to die? This indicates there is flow thru the system, and should in theory mean it is a vacuum problem.

Of course I say in theory because I was pretty sure all my vacuum system was working correctly except the Heat valve. Which turned out to be functional to some extent.